1. Field of the Invention
The present invention relates to a Digital Living Network Alliance (DLNA) system and, in particular, to a method for transforming multimedia contents adaptive to the available data processing capability of the digital media renderer (DMR) of the DLNA network.
2. Description of the Related Art
The Digital Living Network Alliance (DLNA) is an alliance of leading companies, including Microsoft (MS), International Business Machines (IBM), Hewlett-Packard (HP), Intel, Sony, Matsushita, Samsung, etc. in the consumer electronics, mobile, and personal computer industries. An aim of the alliance is to create industry standards that will allow products from all companies to be compatible with each other and to enable a network of electronic devices in the home.
Home networking technologies are now rapidly developing such that consumer electronics, mobile and PC devices are interoperating in a home to enhance and enrich user experiences with various services.
The DLNA defines a PC Internet Network wherein PC and PC peripherals such as a printer communicate. A mobile network of multimedia mobile phones, personal digital assistants (PDAs), Motion Pictures Expert Group (MPEG) 1 Audio Layer 3 (MP3) players, laptop computers, and similar devices provide unparalleled connectivity and freedom of movement into and out of the home environment. A consumer electronics (CE) network includes set-top boxes and traditional consumer electronics.
To deliver interoperability in the digital home, the DLNA has focused on 1) industry collaboration, 2) standards-based interoperability, and 3) compelling products, and has developed the physical media, network transports, media formats, streaming protocols and digital rights management (DRM) on the basis of Universal Plug and Play (UPnP).
FIG. 1 is a block diagram illustrating a conventional DLNA system 100. As shown FIG. 1, the DLNA system 100 is implemented with a plurality of DLNA networks 101. Each includes a Digital Media Server (DMS) 103, a Digital Media Player (DMP) 105, a Digital Media Controller (DMC) 106, and a Digital Media Renderer (DMR) 107.
The DMS 103, DMP 105, and DMC 106 can be a Mobile-Digital Media Server (M-DMP), Mobile-Digital Media Player (M-DMP), and Mobile-Digital Controller (M-DMC), respectively. The M-DMS, M-DMP, and M-DMC can access the DLNA system 100 directly or through an Access Point (AP) 109. The AP is provided with a Mobile Network Connection Function (M-NCF) as the intermediate node for bridging the M-DMS and M-DMP.
The DLNA can be implemented as a home network on the basis of a wired network standard (IEEE 802.3) or a wireless network standard (IEEE 802.11).
The DMS 103, DMP 105, and DMR 107 are interconnected so as to form a wired (IEEE. 802.3) or a wireless network (IEEE 802.11). The digital appliances on the home network can exchange multimedia data such as video and audio data on the basis of IEEE 1394 standard.
The DLNA guidelines, e.g., Home Networked Device Interoperability Guidelines v1.5, are a standard for interconnection of home network appliances. The guidelines classify the DLNA devices into DMS, DMP, DMC, and DMR and define the conditions for connections between the DMS, DMP, DMC, and DMR.
DMS functions as a Media Server Device (MSD) of UPnP AV part, which provides media contents. The main object of the DMS is to enable the control point (CP) as a user interface (UI) application to retrieve digital media content items in the DMS such that the user can display or distribute the contents. The DMS is equipped with a broadcast signal receiver and middleware for broadcast. Some example of DMS includes Video Cassette Recorders (VCRs), Compact Disc (CD) players, Digital Video Disk (DVD) players, Motion Pictures Expert Group 1 (MPEG-1) layer 3 (MP3) players, set-top boxes (STBs), TV tuners, radio tuners, and personal computers (PCs).
The DMR plays content received after being setup by another entity. Some examples of DMR devices include a TV, an audio/video receiver, a video monitor, and remote speakers for music.
The DMP is a DMR or M-DMR including the CP and therefore finds content exposed by the DMS to provide playback and rendering capabilities.
The DLNA guidelines are not a new protocol, but are created by combining the published standards and common protocols. That is, the DLNA adopts IEEE 802.3 for wired communication and IEEE 802.11 for wireless communication as the physical layer. The wired Ethernet has already proved stable, and the use of wireless Ethernet, i.e., Wi-Fi for wireless home networking has become widespread.
DLNA is also implemented with the transmission control protocol/Internet protocol (TCP/IP) for network layer. TCP/IP is a basic network communication protocol used for the elements operating on the Internet and supports transparent data exchange for the application programs operated with various media. For example, PCs or STBs can transmit media contents to the TV located in the other room via an IEEE 802.11 AP which is connected through Ethernet cable. In short, DLNA devices can communicate with each other using TCP/IP through the Internet.
DLNA is, in addition, implemented on the basis of UPnP AV architecture, and on the basis of UPnP Device architecture which is used for locating and controlling devices across the DLNA network, i.e., automatically configuring the IP address and recognizing other devices on the network with reference to the IP address, as well as checking and managing services to be provided.
DLNA further features use of the hypertext transfer protocol (HTTP) for exchanging control messages and transporting files, the extensible markup language (XML) for text message, MPEG2 for video data format, and (Joint Photographic Experts Group) JPEG for still image data format.
One of the key technologies of the DLNA guidelines is UPnP. DMSs and DMPs are addressed and automatically recognized on the basis of the protocol specified in the UPnP device architecture. For example, the DMS providing a list of stored files and broadcasting the data is the UPnP Media Server.
The DLNA guidelines are based on the UPnP and specify the design architecture of digital information products in terms of products such as household appliances, PCs, and wireless devices sharing media content over the wired or wireless home network.
The DLNA guidelines aim for the interoperability among devices, so that systems and products can operate without burdening the user in connection with their operation. The need for interoperability is growing tremendously, and looms as an important factor in deciding the quality of the information devices. This is expressed in ever-growing realization that “The network is a computer.”
When media content is shared by different devices in the DLNA system 100, they transcode/transrate in achieving interoperability. In the conventional DLNA system 100, however, the Media Interoperability Unit (MIU) of the DMS performs a transcoding or transrating scheme fixedly set by the manufacturer or developer of the devices. It is therefore infeasible to check the available capabilities of the devices (for example, DMP or DMR), which complicates optimizing the transcoding or transrating to the available processing capabilities of the devices. Assuring a given quality of service (QoS) of the media contents transmitted from the DMS to the DMR consequently becomes unreliable.